1. Field of the Invention
The present invention relates to cooling systems for slab lasers.
2. Description of the Prior Art
Solid-state laser technology is a very well developed field and numerous embodiments and modes of operation have been demonstrated. Examples of slab lasers are described in U.S. Pat. Nos. 4,719,639 and 4,939,738, the entire contents and disclosures of which are hereby incorporated by reference.
A more recent development of slab lasers has been the pumping of a solid-state laser active medium with an array of diode lasers (diode pumping, for short). These diode pump packages have previously been developed to pump solid-state lasers with good efficiency, but low average power. Developments at Lawrence Livermore National Laboratory (LLNL), particularly with respect to diode cooler technology, have extended diode pumping to the regime of high average power operation.
In order to achieve high-energy storage densities in a solid-state laser, feedback of amplified spontaneous emission (ASE), and parasitic oscillations within the medium (parasitics), must be efficiently suppressed. To this end, edge claddings have been developed and successfully demonstrated on single shot glass disk amplifiers as described by Linford et al. in xe2x80x9cLaser Amplifier Developmentxe2x80x9d in laser Program Annual Report, pp. 2-127 to 2-149 (1977) and by Powell et al in xe2x80x9cPolymer Edge Claddingsxe2x80x9d in Laser Program Annual Report, pp. 6-22 to 6-30 (1985), the entire contents and disclosures of which are hereby incorporate by reference. Two principal techniques for making edge claddings have been used. One technique has been to use an absorbing medium with the same refractive index as the laser medium and diffusion bond the absorbing medium to the laser disk, as described by Linford et al. above. This brings the absorber material and the lasing material in such intimate contact, that the result is the equivalent of a single monolithic block of material. This technique is commonly referred to as a diffusion bonding technique. The other technique is to use a suitably doped absorber and bond the absorber to the laser disk with a type of glue, where the bonding material index matches with the laser disk, as described in Powell et al. above. This is a much more conventional bond where two different materials are now glued together with a distinct glue layer, itself made of a different material than either the absorber or the laser disk. This technique is commonly referred to as a gluing technique.
The amount of ASE light can be a substantial portion of the inversion energy created in the active medium disk or slab. As the edge cladding absorbs ASE light, it is converted into heat. For single shot devices the resulting sudden temperature rise can be sufficient to xe2x80x9cpop offxe2x80x9d the edge cladding if the heat is not distributed over a sufficiently large volume of edge cladding material. In average power laser devices there is now a continuous generation of heat in the edge cladding. As the laser power increases, the power density [W/cm2] of this heat generated in the edge cladding can lead to the destruction of the cladding unless sufficient cooling is provided.
It is a general object of the present invention to provide a cooling system for slab laser edge claddings, which will overcome the above limitations and disadvantages.
It is a further object of the invention to provide cooling system for slab laser edge claddings, which eliminate thermal problems such as focusing and depolarization so that scaling to high average power becomes possible.
It is yet a further object of the present invention to provide a method of cooling the edge cladding of a slab laser which not only removes the heat generated there, but removes it in such a controlled fashion, that an isothermal boundary condition is created which minimizes, and, under ideal conditions, eliminates edge cladding induced stress distortions in the slab/disk itself.
According to a broad aspect of the present invention, there is provided an edge cladding for a slab laser, the edge cladding comprising a cooling channel system therein.
Other objects and features of the present invention will be apparent from the following detailed description of the preferred embodiment.